Sydney Roosters coach Trent Robinson says it was his fault the premiers didn't attempt a late penalty goal in Friday's 9-8 NRL loss to Canterbury, an error of judgment that ultimately proved the difference between the sides.

After Josh Reynolds was penalised on the Bulldogs goalline for offside in the 68th minute with the scores locked at 8-all, the Roosters neglected to take a very gettable shot at goal for James Maloney about 12m in from the sideline on his preferred side.

On the ensuing set of six the Roosters attack couldn't crack the Dogs and a missed field goal from halfback Mitchell Pearce handed Canterbury seven tackles.

From there the Dogs marched upfield and with 10 minutes to go Reynolds calmly slotted the matchwinning field goal at Allianz Stadium before 12,854 fans in a gritty wet weather contest.

"Obviously it was crucial there in the end," Robinson said.

"I think James would've kicked it.

"But that's what happens when you get guys that want to back their attack. But that's what I'm there for, and that's down to me. I've got to make sure the message is really clear for them.

"The boys were geed-up for attack and you want players that are hungry to back themselves.

"I needed to be really firm with them. I needed to get the message to take the two. It's down to me."

Despite the Roosters' second consecutive loss and their 2-3 record to start their premiership defence, Robinson was optimistic.

"Funnily enough I feel proud of the way the guys fought in the last couple of weeks," he said.

"They showed some real character last week, and showed a lot of character again tonight.

"Were not pretty at the moment, but geez they're gritty.

"I feel really proud about the way the guys are playing, the way that they're building their game. Now the cherry-on- top stuff has got to come next.

"Were heading in the right direction with our footy."

Robinson said he was also pleased with Sonny Bill Williams' effort after serving a three-week shoulder charge suspension.

"He was great," Robinson said.

"I thought he added a bit of confidence there that we needed. We are all waiting for Sonny to come back and play some of those plays but like the rest of the team he understands what we are all working on here. It was 80 minutes of him really doing a great job to get his season started again."

The Roosters meet resurgent Parramatta in round six at Pirtek Stadium next Saturday, with prop Jared Waerea-Hargreaves set to return from a one week high tackle ban.